Pneumatic tires with applied air barrier layers

ABSTRACT

A method of manufacturing a tire, the method comprising the steps of providing a cured tire subassembly, the subassembly including a first bead and a second bead, a cured carcass layer extending from the first bead to the second bead, and an optional cured innerliner disposed on the carcass layer; and applying an air barrier composition to the cured carcass layer, or to the cured innerliner if present, to form an air barrier layer.

FIELD OF THE INVENTION

Embodiments of the present invention generally relate to pneumatic tiresand, more particularly, to applying an air barrier layer to a curedpneumatic tire having an innerliner to repair or refresh the innerliner.

BACKGROUND OF THE INVENTION

Pneumatic tires generally include a toroidal rubber body that mates witha wheel to form an inner air chamber. The air chamber is placed underpressure greater than atmospheric pressure in order to inflate the tireand provide sufficient forces to give vertical lift to the wheel andprovide lateral stiffness, which stiffness enhances handling. Thepressure maintained within this inner chamber is therefore an importantaspect of a pneumatic tire.

The inner surface of a pneumatic tire typically includes an elastomericlayer designed to prevent or retard air permeation from the inner airchamber. This inner elastomeric layer, which is often referred to as aninnerliner, typically includes butyl rubber or halobutyl rubber, whichare relatively impermeable to air. The innerliner is often formulatedwith compounding additives and a curing system, and then fabricated intoa thin sheet that is then laminated to the inner surface of a tirecarcass of an uncured tire as the tire is formed. Final cure of thecomposite structure produces a tire having a cured innerliner co-curedwith the carcass.

In addition to or in lieu of an innerliner, it is known to include anair permeation resistant film, which may be referred to as anair-resistant film or air barrier, in order to prevent air permeationfrom the inner air chamber. For example, U.S. Pat. No. 5,738,158 teachesa pneumatic tire having an air permeation prevention layer composed of athin resin film including a thermoplastic polyester elastomer. The airpermeation prevention layer can be adhered to the rubber tire by usingvarious adhesive systems including isocyanate-based adhesives inconjunction with heat and pressure at the time of vulcanization andmolding.

Similarly, an air permeation resistant film has also been proposed inU.S. Pat. No. 8,534,331, which discloses a tire containing a layeredcomposite of sealant and air permeation resistant film. The innersealant includes an organoperoxide depolymerized butyl rubber orpolyurethane, and it is built into an uncured rubber tire andsubsequently cured with the rubber tire.

Despite the presence of an innerliner, many factors can contribute airpressure loss and the inability of a tire to maintain adequate internalpressure. This may include damage to a structural component of a tire.Even upon repair of the structural component, which is common for moreexpensive tires, such as those used on construction vehicles, theability to maintain desirable internal pressure can be problematic.

There is, therefore, a continued need to improve the ability of tires tomaintain adequate air pressure, as well as a need to restore a tire'sability to maintain air pressure after use.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention provide a method ofrestoring a used tire, the method comprising the steps of: providing aused tire, the used tire including a first bead and a second bead, acured carcass layer extending from the first bead to the second bead,and a cured innerliner disposed on the carcass layer; and applying anair barrier composition to the innerliner to form an air barrier layerwithin the used tire.

Other embodiments of the present invention provide a method of repairinga tire, the method comprising the steps of: repairing a damaged tire toprovide a repaired tire, the repaired tire including a first bead and asecond bead, a carcass layer extending from the first bead to the secondbead, and an innerliner disposed on the carcass layer; and applying anair barrier composition to the innerliner to form an air barrier layer.

Still other embodiments of the present invention provide a method ofmanufacturing a tire, the method comprising the steps of: providing acured tire subassembly, the subassembly including a first bead and asecond bead, a cured carcass layer extending from the first bead to thesecond bead, and a cured innerliner disposed on the carcass layer; andapplying an air barrier composition to the cured innerliner to form anair barrier layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a tire according to one or moreembodiments of the invention.

FIG. 2 is a cross-sectional view of a tire according to one or moreembodiments of the invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the present invention are based, at least in part, onpneumatic tires that include an applied air barrier layer, which is anair barrier layer applied after the tire has been manufactured (i.e.after curing of the tire). In one or more embodiments, the air barrieris applied to a tire that has been in service to alleviate issuesresulting in loss of internal air pressure. Accordingly, embodiments ofthe invention are directed toward a method of applying an air barrierlayer to the interior of a cured tire. In one or more embodiments,application of the air barrier layer may take place following a repairmade to one or more components of a tire that has been in service.

Tire Structure

Aspects of the invention can be described with reference to FIGS. 1 and2. As specifically shown in FIG. 1, tire 11 includes carcass 13extending between a pair of axially-spaced beads 15, 15′. Carcass 13includes opposed turn-up portions 14, 14′, which thereby cause body ply13 to surround bead filler portions 16, 16′, respectively. Abrasionstrips 17, 17′ partially encase body ply 13 at or near beads 15, 15′.Tire 11 further includes opposing sidewalls 19, 19′, and tread portion21, which forms the outermost circumferential surface of tire 11.Subtread 23 is disposed below tread 21, undertread 25 is disposed belowsubtread 23, and belt package 27 is disposed below undertread 25. Beltpackage 27, which may include a plurality of belts (not shown), ispositioned above carcass 13, which itself may include one or more bodyplies (not shown). Innerliner 29 may include butyl rubber or halobutylrubber and is disposed on the interior of carcass 13 relative to tread21. As the skilled person will appreciate, tire 11 may also includevarious other components, which are not shown, such as, but not limitedto, tread shoulders, cap plies, belt wedges, and belt shoulders. Withreference to FIG. 2, tire 11 is without innerliner 29, and thereforetire 11 may derive from a tire subassembly, which is prepare in theabsence of separate and distinct innerliner.

According to embodiments of the present invention, tire 11 furtherincludes air barrier layer 31. As shown in FIG. 1, air barrier layer 31is disposed on innerliner 29 on the interior side 30 of tire 11 relativeto tread 21 (i.e. opposite tread 21). Air barrier layer 31 generallyextends from a location proximate to first abrasion strip 17 to alocation proximate second abrasion strip 17′ (i.e., generally throughoutthe entire inner surface of carcass 13).

In alternate embodiments, as shown in FIG. 2, air barrier layer 31 isdisposed directly on carcass 13 on the interior side 30 of tire 11relative to tread 21 (i.e. opposite tread 21). Air barrier layer 31generally extends from a location proximate to first abrasion strip 17to a location proximate second abrasion strip 17′ (i.e., generallythroughout the entire inner surface of carcass 13).

Although not shown in the drawings, the tires of the present inventionmay include a layer of an anti-tack composition applied to at least oneof the innermost layers of the tire. In particular embodiments, theanti-tack composition, which may be referred to as an anti-tack coating,may be applied to cover an exposed air barrier layer. In particularembodiments, the anti-tack composition may include a compositionincluding a polymeric resin selected from acrylic resins and/or vinylacetate copolymers as disclosed in U.S. Publication No. 2003/0230369,which is incorporated herein by reference.

In yet other embodiments, a tires of the present invention may includesidewall inserts (not shown in the Figs.) of the type generally known inthe art for producing a self-supporting run flat tire. In this respect,U.S. Pat. Nos. 6,488,797; 6,834,696; and 5,769,980 are each incorporatedherein by reference. In one or more embodiments, the air barrier layercan be disposed on the sidewall inserts.

Air Barrier Layer

In one or more embodiments, the air barrier layer (e.g. air barrierlayer 31) may be generally described with respect to one or moreproperties of the air barrier layer.

The air barrier layer of one or more embodiments of the presentinvention (e.g. air barrier layer 31) generally includes a polymericlayer that has low permeability to air; i.e. low permeability to oxygen,nitrogen and carbon dioxide. The low permeability to air may bedescribed in terms of the oxygen permeability (P(O₂)), which may also bereferred to as oxygen permeance. The P(O₂) number quantifies the amountof oxygen that can pass through the polymeric layer under a specific setof circumstances and is generally expressed in units ofcc·mm/m²·day·atm. This is a standard unit of permeation measured ascubic centimeters of oxygen permeating through one millimeter thicknessof a sample, of an area of a square meter, over a 24 hour period, undera partial pressure differential of one atmosphere at a specifictemperature and relative humidity (R.H.) conditions. In one or moreembodiments, the oxygen permeability (P(O₂)) may be measured inaccordance with ASTM method F1927-14 which measures O₂ transmissionrates at 23° C. at 50% relative humidity.

In one or more embodiments, the air barrier layer of the tires of thepresent invention (e.g. air barrier layer 31) may have a P(O₂) of lessthan 500, in other embodiments less than 250, in other embodiments lessthan 150, in other embodiments less than 100, in other embodiments lessthan 80, and in other embodiments less than 50, cc·mm/m²·day·atm. In oneor more embodiments, the air barrier layer may have a P(O₂) of fromabout 0.01 to about 500 cc·mm/m²·day·atm, in other embodiments fromabout 0.1 to about 100 cc·mm/m²·day·atm, in other embodiments from about50 to about 100 cc·mm/m²·day·atm, and in other embodiments from about 50to about 80 cc·mm/m²·day·atm.

In one or more embodiments, the air barrier layer of the tires of thepresent invention (e.g. air barrier layer 31) may have advantageousadhesion to another component of the tire. The adhesion may be measuredby ASTM D903 or ASTM D1876.

In one or more embodiments, the air barrier layer of the tires of thepresent invention (e.g. air barrier layer 31) may have an adhesion tothe carcass (e.g. carcass 13) of more than 5 N/mm, in other embodimentsmore than 10 N/mm, in other embodiments more than 15 N/mm, in otherembodiments more than 30 N/mm, and in other embodiments more than 50N/mm. In one or more embodiments, the air barrier layer may have anadhesion to the carcass of from about 1 N/mm to about 50 N/mm, in otherembodiments from about 5 N/mm to about 30 N/mm, and in other embodimentsfrom about 5 N/mm to about 15 N/mm.

In one or more embodiments, the air barrier layer of the tires of thepresent invention (e.g. air barrier layer 31) may have an adhesion tothe innerliner (e.g. innerliner 29) of more than 5 N/mm, in otherembodiments more than 10 N/mm, in other embodiments more than 15 N/mm,in other embodiments more than 30 N/mm, and in other embodiments morethan 50 N/mm. In one or more embodiments, the air barrier layer may havean adhesion to the innerliner of from about 1 N/mm to about 50 N/mm, inother embodiments from about 5 N/mm to about 30 N/mm, and in otherembodiments from about 5 N/mm to about 15 N/mm.

The air barrier layer of one or more embodiments of the presentinvention (e.g. air barrier layer 31) may be generally characterizedwith respect to the composition of the air barrier layer.

Practice of one or more embodiments of the invention is not necessarilylimited by the selection of any particular air barrier composition forthe air barrier layer. Various air barrier compositions are known forthis particular purpose, as generally disclosed in U.S. Pat. Nos.5,840,825; 6,309,757; 6,521,706; 7,730,919; 7,798,188; 7,905,978;7,954,528; 7,976,666; 8,021,730; 8,534,331; and 8,835,592; and U.S.Publication Nos. 2008/0047646; 2009/0038727; 2008/0152935; 2010/0174032;and 2015/0368512, which are incorporated herein by reference.

In one or more embodiments, an air barrier composition may include twoor more polymeric components, each having a distinct glass transitiontemperature (T_(g)). In one or more embodiments, the two or morepolymeric components may be sufficiently blended to provide the blendedcomposition with a glass transition temperature that is distinct fromthe glass transition temperatures of the two or more polymericcomponents. In one or more embodiments, the air barrier layercomposition of one or more embodiments of the present invention includesat least one glass transition temperature (T_(g)) peak, from onecomponent of the air barrier layer, of less than −20° C., in otherembodiments, less than −30° C., and in other embodiments, less than −40°C. Glass transition temperature may be measured by differential scanningcalorimetry. In these or other embodiments, the air barrier layercomposition includes a second glass transition temperature (T_(g)) peakof greater than 0° C., in other embodiments, greater than 10° C., and inother embodiments greater than 20° C.

In one or more embodiments, an air barrier composition is a polymericcomposition including a thermoplastic and elastomeric component. In oneor more embodiments, the air barrier layer is phase-separated polymericsystem wherein an elastomeric component is phase separated from athermoplastic component (e.g. soft and hard domains). In certainembodiments, the thermoplastic component is dispersed within theelastomeric component. In other embodiments, the elastomeric componentis dispersed within the thermoplastic component. In yet otherembodiments, the thermoplastic component and the elastomeric componentare co-continuous. An exemplary embodiment includes a first phase with apolyurethane and a second phase with a polysulfide elastomer, and incertain embodiments, the polyurethane provides the continuous phasewhile polysulfide forms the discontinuous phase.

In one or more embodiments, an air barrier layer may be formed from anair barrier coating composition that is an aqueous dispersion or latex.In one or more embodiments, this aqueous dispersion may include morethan 10 wt. % solids, in other embodiments more than 20 wt. % solids, inother embodiments more than 25 wt. % solids, in other embodiments morethan 40 wt. % solids, and in other embodiments more than 45, wt. %solids. In one or more embodiments, an aqueous medium having adispersion of one or more polymeric materials therein may include fromabout 10 to about 45 wt. % solids, in other embodiments from about 20 toabout 40 wt. % solids, and in other embodiments from about 20 to about25 wt. % solids.

In particular embodiments, the air barrier layer includes a blend ofpolyurethane and elastomeric polymer. As disclosed in U.S. Publ. No.2010/0174032, which is incorporated herein by reference, thepolyurethane may include a polyurethane wherein at least 30 wt % of themer units derive from a meta-substituted aromatic material, such as ameta-substituted aromatic isocyanate. In these or other embodiments, asdisclosed in U.S. Publ. No. 2015/0368512, which is incorporated hereinby reference, these compositions may derive from aqueous dispersions ofpolyurethane, a polysulfide, and a curative such as magnesium oxide. Inone or more embodiments, an air barrier composition can include aqueousdispersed polyurethanes. In one or more embodiments, an air barriercomposition can include aqueous dispersed polyvinylidene chloridecopolymers.

In one or more embodiments, the polyurethane can have reactivefunctional groups. As used here, a reactive functional group refers toan atom, group of atoms, functionality, or group having sufficientreactivity to form at least one covalent bond with another reactivegroup in a chemical reaction. For example, a polyurethane can includereactive functional groups that are reactive with themselves or withanother component, such as a crosslinker. Examples of reactivefunctional groups include mercapto or thiol groups, hydroxyl groups,(meth)acrylate groups, carboxylic acid groups, amine groups, epoxidegroups, carbamate groups, amide groups, urea groups, isocyanate groups(including blocked isocyanate groups), and combinations thereof.

In one or more embodiments, a polyurethane can be substantially free orcompletely free of reactive functional groups. As used here, the termsubstantially free means a polyurethane may contain less than 1000 partsper million (ppm), and completely free means less than 20 parts perbillion (ppb), of reactive functional groups. In one or moreembodiments, a polyurethane may include aqueous dispersed polyurethanesthat are completely free of reactive functional groups.

In one or more embodiments, an air barrier composition may includethermoplastic polymer (e.g. polyurethane) in an amount of more than 5wt. %, in other embodiments, more than 10 wt. %, and in otherembodiments, more than 15 wt. %, based on the total solid weight of theair barrier composition. In one or more embodiments, an air barriercomposition may include thermoplastic polymer in an amount of less than75 wt. %, in other embodiments, less than 50 wt. %, in otherembodiments, less than 35 wt. %, and in other embodiments, less than 20wt. %, based on the total solid weight of the air barrier composition.In one or more embodiments, an air barrier composition may includethermoplastic polymer in an amount of from about 5 wt. % to about 75 wt.%, in other embodiments, from about 10 wt. % to about 50 wt. %, and inother embodiments, from about 10 wt. % to about 20 wt. %, based on thetotal solid weight of the air barrier composition. The weight % may bedetermined by standard gel permeation chromatography.

In one or more embodiments, an air barrier composition includes apolysulfide. The polysulfide may act as an elastomeric material in theair barrier layer. The term polysulfide refers to a polymer thatcontains one or more disulfide linkages (i.e. —[S—S]—) linkages, in thepolymer backbone, and/or in the terminal or pendant positions on thepolymer chain. A polysulfide polymer can have two or more sulfur-sulfurlinkages. A polysulfide can also include a mixture of primary disulfidesand higher rank polysulfides such as tri and tetra polysulfide linkages(S—S—S; S—S—S—S). Further, a polysulfide can include mercapto or thiolfunctional groups (an —SH group). For instance, a polysulfide can berepresented by chemical formula (I)

where each R can independently be —(CH₂—CH₂—O—CH₂—O—CH₂—CH₂)— anda+b+c+d can be a number up to and including 1,000. A polysulfide thatcan be used with the present invention can also be represented bychemical formula (II):

H(SC₂H₄OCH₂OC₂H₄S)_(n)H   (II),

where n can be a number up to and including 1,000. Exemplarypolysulfides are those commercially available under the trade nameTHIOPLAST®, a liquid polysulfide polymer with mercapto end groupssupplied by Akzo Nobel, Greiz, Germany.

In one or more embodiments, a polysulfide can have a glass transitiontemperature (T_(g)) of less than 0° C., as measured by differentialscanning calorimetry. In other embodiments, a polysulfide can have aglass transition temperature (T_(g)) of less than −10° C., in otherembodiments, less than −20° C., and in other embodiments, less than −30°C.

In one or more embodiments, an air barrier composition may besubstantially free or may be completely free of all other elastomericmaterials, except for polysulfides. As used here, the term substantiallyfree means an air barrier composition may contain less than 1000 partsper million (ppm), and completely free means less than 20 parts perbillion (ppb), of all other elastomeric materials, except forpolysulfides.

In other embodiments, an air barrier composition may include apolysulfide and an additional elastomeric material. Exemplary additionalelastomeric materials that can be used include acrylonitriles, naturaland synthetic rubbers such as aqueous butyl rubber dispersions, styrenicthermoplastic elastomers, polyamide elastomers, thermoplasticvulcanizates, flexible acrylic polymers, and combinations thereof.

In one or more embodiments, an air barrier composition may includeelastomeric polymer (e.g. polysulfide) in an amount of more than 5 wt.%, in other embodiments, more than 10 wt. %, in other embodiments, morethan 15 wt. %, in other embodiments, more than 25 wt. %, and in otherembodiments, more than 50 wt. %, based on the total solid weight of theair barrier composition. In one or more embodiments, an air barriercomposition may include elastomeric polymer in an amount of less than 80wt. %, in other embodiments, less than 75 wt. %, and in otherembodiments, less than 70 wt. %, based on the total solid weight of theair barrier composition. In one or more embodiments, an air barriercomposition may include elastomeric polymer in an amount of from about 5wt. % to about 80 wt. %, in other embodiments, from about 25 wt. % toabout 75 wt. %, and in other embodiments, from about 50 wt. % to about70 wt. %, based on the total solid weight of the air barriercomposition. The weight % may be determined by standard gel permeationchromatography.

In one or more embodiments, an air barrier composition may include oneor more inorganic materials. As used herein, an inorganic materialrefers to materials and substances that are not organic, i.e., do notinclude carbon-based materials. The one or more inorganic materials mayinclude one or more platy inorganic fillers. As used herein, a platyinorganic filler refers to an inorganic material in the platy form. Theterm platy refers to a structure in which one dimension is substantiallysmaller than the two other dimensions of the structure resulting in aflat type appearance. The platy inorganic fillers are generally in theform of stacked lamellae, sheets, platelets, or plates with a relativelypronounced anisometry. The inorganic materials, such as the platyinorganic fillers, can further improve the barrier performance of theresulting air barrier layer by reducing the permeability of liquids andgases.

Suitable platy inorganic fillers can include those having a high aspectratio. Suitable high aspect ratio platy inorganic fillers include, forexample, vermiculite, mica, talc, wollastonite, chlorite, metal flakes,platy clays, and platy silicas. In one or more embodiments, a filler hasa diameter of from 1 to 20 microns, in other embodiments, from 2 to 10microns, and in other embodiments, from 2 to 5 microns. In one or moreembodiments, the aspect ratio of the fillers can be at least 5:1, inother embodiments, at least 10:1, and in other embodiments, at least20:1. For example, mica flakes may have an aspect ratio of 20:1, talcmay have an aspect ratio of 10:1 to 20:1, and vermiculite may have anaspect ratio of from 200:1 to 10,000:1.

In one or more embodiments, as disclosed in U.S. Pat. No. 8,534,331, theair barrier layer includes a two-phase system where an elastomer isdispersed within a thermoplastic matrix. In certain embodiments, thethermoplastic may include nylon and the elastomer may include butylrubber and/or a sulfur-curable diene based elastomer.

In one or more embodiments, an air barrier composition may include arheology agent. As generally known to those skilled in the art, rheologyagents are those materials that help to improve the flow properties of acomposition. An exemplary rheology agent is a polypropylene glycolsolution of a urea modified polyurethane

In one or more embodiments, the air barrier layer of the tires of thepresent invention (e.g. air barrier layer 31) may have a thickness ofmore than 8 mils, in other embodiments more than 10 mils, in otherembodiments more than 14 mils, and in other embodiments more than 16mils. In these or other embodiments, the air barrier layer may have athickness of less than 28 mils, in other embodiments less than 25 mils,in other embodiments less than 20 mils, and in other embodiments lessthan 18 mils. In one or more embodiments, the air barrier layer may havea thickness of from about 5 mils to about 28 mils, in other embodimentsfrom about 8 mils to about 25 mils, in other embodiments from about 10mils to about 22 mils, and in other embodiments from about 15 mils toabout 20 mils.

In one or more embodiments, the composition of the air barrier layer isnot sulfur crosslinked to an adjacent tire component. For example, inone or more embodiments, the composition of the air barrier layer is notsulfur crosslinked to the innerliner. In other embodiments, thecomposition of the air barrier layer is not sulfur crosslinked to thecarcass.

In one or more embodiments, the composition of the air barrier layer issulfur crosslinked to an adjacent tire component. For example, in one ormore embodiments, the composition of the air barrier layer is sulfurcrosslinked to the innerliner. In other embodiments, the composition ofthe air barrier layer is sulfur crosslinked to the carcass.

Other Tire Components

The various tire components associated with the tires of the presentinvention may be prepared from conventional vulcanizable compositions ofmatter. Accordingly, practice of one or embodiments of the presentinvention does not alter conventional practice for preparing the varioustire components. Generally speaking, these vulcanizable compositions mayinclude an elastomer, a filler, and a curative, as well as otheringredients including, but not limited to, antidegradants, cureactivators, cure accelerators, oils, resins, plasticizers, pigments,fatty acids, zinc oxide, and peptizing agents.

Rubber

As suggested above, the various tire components can be prepared using avulcanizable composition that includes a rubber. In one or moreembodiments, the rubber, which may also be referred to as a vulcanizablerubber or elastomer, may include those polymers that can be vulcanizedto form compositions possessing rubbery or elastomeric properties. Theseelastomers may include natural and synthetic rubbers. The syntheticrubbers typically derive from the polymerization of conjugated dienemonomer, the copolymerization of conjugated diene monomer with othermonomer such as vinyl-substituted aromatic monomer, or thecopolymerization of ethylene with one or more α-olefins and optionallyone or more diene monomers.

Exemplary elastomers include natural rubber, synthetic polyisoprene,polybutadiene, polyisobutylene-co-isoprene, neoprene,poly(ethylene-co-propylene), poly(styrene-co-butadiene),poly(styrene-co-isoprene), poly(styrene-co-isoprene-co-butadiene),poly(isoprene-co-butadiene), poly(ethylene-co-propylene-co-diene),polysulfide rubber, acrylic rubber, urethane rubber, silicone rubber,epichlorohydrin rubber, and mixtures thereof. These elastomers can havea myriad of macromolecular structures including linear, branched, andstar-shaped structures. These elastomers may also include one or morefunctional units, which typically include heteroatoms. In particularembodiments, a vulcanizable composition includes a blend of naturalrubber and synthetic diene rubber such as polybutadiene. In otherembodiments, a vulcanizable composition includes olefinic rubber suchethylene-propylene-diene rubber (EPDM).

Filler

As suggested above, the various tire components can be prepared using avulcanizable composition that includes a filler. The filler may includeone or more conventional reinforcing or non-reinforcing fillers. Forexample, useful fillers include carbon black, silica, alumina, andsilicates such as calcium, aluminum, and magnesium silicates.

In one or more embodiments, carbon blacks include furnace blacks,channel blacks, and lamp blacks. More specific examples of carbon blacksinclude super abrasion furnace (SAF) blacks, intermediate super abrasionfurnace (ISAF) blacks, high abrasion furnace (HAF) blacks, fastextrusion furnace (FEF) blacks, fine furnace (FF) blacks,semi-reinforcing furnace (SRF) blacks, medium processing channel blacks,hard processing channel blacks, conducting channel blacks, and acetyleneblacks. Representative carbon blacks useful in one or more embodimentsmay include those designated by ASTM D1765 as N326, N330, N339, N343,N347, N351, N358, N550, N650, N660, N762, N772, and N774.

In particular embodiments, the carbon blacks may have a surface area(EMSA) of at least 20 m²/g, in other embodiments at least 35 m²/g, inother embodiments at least 50 m²/g, in other embodiments at least 60m²/g; surface area values can be determined by ASTM D-1765 using thecetyltrimethylammonium bromide (CTAB) technique. In particularembodiments, a vulcanizable composition includes carbon black fillerhaving a surface area (EMSA) of from about 60 to about 110 m²/g. Thecarbon blacks may be in a pelletized form or an unpelletized flocculentform. The preferred form of carbon black may depend upon the type ofmixing equipment used to mix the rubber compound.

In one or more embodiments, the filler may include silica. When silicais used as a filler, the silica may be employed in conjunction with acoupling agent. In these or other embodiments, the silica may be used inconjunction with a silica dispersing agent.

In one or more embodiments, useful silicas include, but are not limitedto, precipitated amorphous silica, wet silica (hydrated silicic acid),dry silica (anhydrous silicic acid), fumed silica, calcium silicate, andthe like. Other suitable fillers include aluminum silicate, magnesiumsilicate, and the like. In particular embodiments, the silica is aprecipitated amorphous wet-processed hydrated silica. In one or moreembodiments, these silicas are produced by a chemical reaction in water,from which they are precipitated as ultra-fine, spherical particles.These primary particles are believed to strongly associate intoaggregates, which in turn combine less strongly into agglomerates.

Some commercially available silicas that may be used include Hi-Sil™215, Hi-Sil™ 233, and Hi-Sil™ 190 (PPG Industries, Inc.; Pittsburgh,Pa.). Other suppliers of commercially available silica include GraceDavison (Baltimore, Md.), Degussa Corp. (Parsippany, N.J.), RhodiaSilica Systems (Cranbury, N.J.), and J.M. Huber Corp. (Edison, N.J.).

In one or more embodiments, silicas may be characterized by theirsurface areas, which give a measure of their reinforcing character. TheBrunauer, Emmet and Teller (“BET”) method (described in J. Am. Chem.Soc., vol. 60, p. 309 et seq.) is a recognized method for determiningthe surface area. The BET surface area of silica is generally less than450 m²/g. Useful ranges of surface area include from about 32 to about400 m²/g, about 100 to about 250 m²/g, and about 150 to about 220 m²/g.

In one or more embodiments, the pH of silica may be from about 5 toabout 7 or slightly over 7, or in other embodiments from about 5.5 toabout 6.8.

In one or more embodiments, useful silica coupling agents includesulfur-containing silica coupling agents. Examples of sulfur-containingsilica coupling agents include bis(trialkoxysilylorgano)polysulfides ormercapto-organoalkoxysilanes. Types ofbis(trialkoxysilylorgano)polysulfides includebis(trialkoxysilylorgano)disulfide andbis(trialkoxysilylorgano)tetrasulfides. Exemplary silica dispersing aidsinclude, but are not limited to an alkyl alkoxysilane, a fatty acidester of a hydrogenated or non-hydrogenated C₅ or C₆ sugar, apolyoxyethylene derivative of a fatty acid ester of a hydrogenated ornon-hydrogenated C₅ or C₆ sugar, and mixtures thereof, or a mineral ornon-mineral additional filler.

Curative

As suggested above, the various tire components can be prepared using avulcanizable composition that includes a curative. A multitude of rubbercuring agents (also called vulcanizing agents) may be employed,including sulfur or peroxide-based curing systems. Curing agents aredescribed in Kirk-Othmer, ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY, Vol. 20,pgs. 365-468, (3rd Ed. 1982), particularly Vulcanization Agents andAuxiliary Materials, pgs. 390-402, and A. Y. Coran, Vulcanization,ENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING, (2^(nd) Ed. 1989),which are incorporated herein by reference. In one or more embodiments,the curative is sulfur. Examples of suitable sulfur vulcanizing agentsinclude “rubbermaker's” soluble sulfur; sulfur donating vulcanizingagents, such as an amine disulfide, polymeric polysulfide or sulfurolefin adducts; and insoluble polymeric sulfur. Vulcanizing agents maybe used alone or in combination.

In one or more embodiments, the curative is employed in combination witha cure accelerator. In one or more embodiments, accelerators are used tocontrol the time and/or temperature required for vulcanization and toimprove properties of the vulcanizate. Examples of accelerators includethiazol vulcanization accelerators, such as 2-mercaptobenzothiazol,dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazyl-sulfenamide (CBS),and the like, and guanidine vulcanization accelerators, such asdiphenylguanidine (DPG) and the like.

Other ingredients that are typically employed in rubber compounding mayalso be added to the rubber compositions employed for fabricating thevarious components of the tires of the invention. These include oils,plasticizer, waxes, scorch inhibiting agents, processing aids, zincoxide, tackifying resins, reinforcing resins, fatty acids such asstearic acid, and peptizers. In particular embodiments, the oils thatare employed include those conventionally used as extender oils, whichare described above. Useful oils or extenders that may be employedinclude, but are not limited to, aromatic oils, paraffinic oils,naphthenic oils, vegetable oils other than castor oils, low PCA oilsincluding MES, TDAE, and SRAE, and heavy naphthenic oils.

Preparing Tires

The tires, as well as the tire subassemblies, that are modifiedaccording the present invention by application of an air barrier layermay be fabricated by employing conventional rubber shaping, molding, andcuring techniques. In one or more embodiments, vulcanization can beeffected by heating the vulcanizable composition within a mold. In oneor more embodiments, the composition can be heated at an internaltemperature from about 120° C. to about 180° C.

The cured or crosslinked rubber compositions (i.e., vulcanizates)generally include three-dimensional polymeric networks that arethermoset. Other ingredients, such as processing aids and fillers, aregenerally dispersed throughout the vulcanized network. Tire preparationis discussed in U.S. Pat. Nos. 5,866,171, 5,875,527, 5,931,211, and5,971,046, which are incorporated herein by reference. Rubbercompounding techniques and the additives employed therein are generallyknown as also disclosed in The Compounding and Vulcanization of Rubber,in Rubber Technology (2^(nd) Ed. 1973), which is incorporated herein byreference.

As suggested in the Figures, the tires of the present invention can beprepared with or without an innerliner component. In one or moreembodiments, where an innerliner is present, the innerliner is co-curedand therefore sulfur-crosslinked to the other rubber components such asthe adjacent carcass or body plies.

Method of Applying Air Barrier Layer

As indicated above, the air barrier layer associated with the tires ofthis invention is applied after a cured tire or subassembly is provided.In other words, the air barrier layer is applied to a tire orsubassembly that has undergone the vulcanization (i.e. curing) processassociated with the manufacture of the tire.

Thus, once a cured tire or subassembly has been provided, the airbarrier layer is applied to the tire or subassembly. This layer may beapplied to the tire or subassembly by the direct application of a liquidor otherwise flowable composition (e.g., molten extrudate) that forms awet or green coating that then dries or cures to form the air barrierlayer. In other embodiments, the air barrier layer is applied through atransfer coating; i.e., a liquid or otherwise flowable composition thatforms a wet or green coating is applied to a transfer substrate, such asa release member, the wet or green coating is allowed to dry orotherwise cure into a solids composition, and then the solidscomposition is applied to the tire or subassembly and the transfersubstrate is removed.

As suggested by the drawings, in one or more embodiments, the airbarrier may be applied directly to the innerliner of a cured tire orsubassembly. In other embodiments, where the cured tire or subassemblyis provided without a separate innerliner, the air barrier layer may beapplied directly to the body ply or tire carcass.

In one or more embodiments, an intermediary layer is disposed below theair barrier (i.e., interior to the air barrier layer). For example, anintermediary layer may include a primer layer or a release agent layer,or a combination thereof.

In one or more embodiments, a primer layer may be present where there isa desire to improve the adhesion of the air barrier layer to anothercomponent of the tire. An exemplary primer layer may include acomposition including butyl rubber, such as those disclosed in U.S. Pat.No. 5,985,981, which is incorporated herein by reference.

As the skilled person will appreciate, release agents, such as siliconeor silicone-based compositions, may be used during the tiremanufacturing process. As a result, practice of the present inventionmay include applying the air barrier layer to a layer or film of releaseagent. In other embodiments, efforts may be made to remove or otherwisetreat the release agents prior to application of the air barrier layer.As a result, practice of the present invention may include applicationof the air barrier layer to a residue of a release agent; for example, aresidue resulting from the chemical treatment of a release agent layeror film.

In those embodiments where the air barrier layer derives from a liquidor otherwise flowable composition, the composition may be applieddirectly to the tire, or applied to a transfer member, by using avariety of techniques to form a wet or green coating layer. For example,the liquid or flowable composition may be applied by spraying,roll-coating, knife coating, extrusion, or similar techniques. In one ormore embodiments, the air barrier composition has a viscosity that islow enough to allow the composition to be spray applied to theinnerliner or carcass.

Following application of the air barrier layer to the interior of thetire, further steps may be taken to expedite drying or curing of the airbarrier layer. In certain embodiments, the composite (i.e. tire with airbarrier layer) is allowed to air dry at standard conditions oftemperature and pressure. In other embodiments, the composite is heated(e.g. to 100° C.-150° C.).

Where the air barrier layer is applied to the cured tire via a transfercoating, the solids composition can be mated to the innerliner orcarcass layer by using standard techniques that may include, forexample, mating the solids composition to the carcass or innerliner andthen applying pressure, such as by way of a roller.

INDUSTRIAL APPLICABILITY

In one or more embodiments, tires of the present invention, which mayalso be referred to as pneumatic tires, may include passenger tires,truck/bus tires, off-road tires, agricultural tires and industrialtires. These tires and their common and distinct features are well knownin the art. For example, agricultural and industrial tires include thosedescribed in, for example, U.S. Patent Publication No. 2005/0139302 A1,and U.S. Pat. Nos. 3,844,326, 4,202,391, 4,611,647, 4,791,971,4,649,976, 5,046,541, 5,063,573, 5,188,683, 5,337,814, 5,337,816,5,421,388, 5,464,050, 5,901,765, 6,179,027, 6,260,594, 6,263,933,6,450,221, and 6,481,479, each of which is hereby incorporated byreference. All terrain or off-road tires include those described in, forexample, U.S. Pat. Nos. 4,881,586, 5,259,429, 5,318,086, 5,375,640,6,293,323, 6,298,890, 6,401,774, 6,799,617, and 6,929,044, each of whichis hereby incorporated by reference.

As indicated above, one or more embodiments of the present inventionincludes the application of an air barrier layer to a tire that has beenin service, which tire may also be referred to as a used tire or agedtire. Application of the air barrier layer to a used tire can extend theuseful life of the tire relative to the tire's ability to maintainadequate tire pressure.

In one or more embodiments, aged tires may be characterized by run time,which may also be referred to as service time. Accordingly, the processof certain embodiments of the invention may include applying an airbarrier layer to a cured tire having a run time of at least 2,000kilometers, in other embodiments at least 5,000 kilometers, and in otherembodiments at least about 10,000 kilometers.

In these or other embodiments, aged tires may include those tires thatare experiencing air retention issues including air pressure loss overtime. As a skilled person will appreciate, air pressure loss over timecan be determined by ASTM F1112. Accordingly, the process of certainembodiments of the invention may include applying an air barrier layerto a cured tire experiencing an air pressure loss (per ASTM F1112) of atleast 2% per month, in other embodiments at least 4% per month, and inother embodiments at least 6% per month.

In these or other embodiments, aged tires may include those tires thatare characterized by a tread wear loss. As a skilled person willappreciate, tread wear is conventionally measured based upon a change intread depth (i.e. tread loss) relative to a virgin tire. In one or moreembodiments, the processes of the present invention treat tires thathave experienced a tread loss of at least 1/64″, in other embodiments atleast 1/32″, and in other embodiments at least 1/16″.

As also indicated above, one or more embodiments of the presentinvention includes the application of an air barrier layer to a tirethat has recently been repaired; e.g. the application of the air barrierlayer may coincide with or be included in the process of repairing atire.

Practice of embodiments of the invention may not necessarily be limitedby the type of repair that a particular tire may have undergone. Oneexemplary type of repair may include application of a patch rubberelement, which may include a fabric reinforcement (e.g. patch cords).The patch rubber can be attached with adhesive to the inner side of thetire in the damaged portion of the carcass ply where, for example, a plycord has broken. Various rubber adhesive can be used to secure the patchincluding those adhesives available, for example, under the tradenameCHEMLOK (LORD Corporation). In these or other embodiments, a repair mayinclude installation of a plug to repair a puncture within one or moretire components. As a skilled person will appreciate, these plugs mayinclude cured rubber elements that may be fabric reinforced. Inparticular embodiments, a plug is used in conjunction with a patch.Other techniques for repairing tires are known in the art includingthose disclosed in U.S. Pat. Nos. 8,784,588; 8,714,219; 5,695,577;5,247,981; 4,923,543; and 2,229,878, U.S. Publication Nos. 2013/0220503;2010/0258237; and 2009/0229737, which are all incorporated herein byreference.

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

1. A method of restoring a used tire, the method comprising the stepsof: (i) providing a used tire, the used tire including a first bead anda second bead, a cured carcass layer extending from the first bead tothe second bead, and a cured innerliner disposed on the carcass layer;and (ii) applying an air barrier composition to the innerliner to forman air barrier layer within the used tire.
 2. The method of claim 1,where the step of applying an air barrier composition includes sprayingan air barrier composition.
 3. The method of claim 2, where the airbarrier composition comprises a polymeric layer having low permeabilityto air.
 4. The method of claim 2, wherein the air barrier compositionincludes a phase separated blend of elastomer and thermoplastic resin.5. The method of claim 1, where the used tire has been in service for atleast 2,000 kilometers.
 6. The method of claim 1, where the used tireexperiences an air pressure loss (per ASTM F1112) of at least 2 psi permonth
 7. The method of claim 1, where the used tire has a tread wearloss of at least 1/64″.
 8. A method of repairing a tire, the methodcomprising the steps of: (i) repairing a damaged tire to provide arepaired tire, the repaired tire including a first bead and a secondbead, a carcass layer extending from the first bead to the second bead,and an innerliner disposed on the carcass layer; and (ii) applying anair barrier composition to the innerliner to form an air barrier layer.9. The method of claim 8, where the step of applying an air barriercomposition includes spraying an air barrier composition.
 10. The methodof claim 8, where the air barrier composition comprises a polymericlayer having low permeability to air.
 11. The method of claim 8, whereinthe air barrier composition includes a phase separated blend ofelastomer and thermoplastic resin.
 12. The method of claim 8, where thestep of repairing includes inserting a plug into a puncture within thetire
 13. The method of claim 8, wherein the step of repairing thedamaged tire includes repairing a component selected from the groupconsisting of the tread, carcass, and innerliner.
 14. The method ofclaim 8, wherein the step of applying is performed by extruding the airbarrier composition on to the carcass layer.
 15. A method ofmanufacturing a tire, the method comprising the steps of: (i) providinga cured tire subassembly, the subassembly including a first bead and asecond bead, a cured carcass layer extending from the first bead to thesecond bead, and a cured innerliner disposed on the carcass layer; and(ii) applying an air barrier composition to the cured innerliner to forman air barrier layer.
 16. The method of claim 15, where the step ofapplying an air barrier composition includes spraying an air barriercomposition.
 17. The method of claim 15, where the air barriercomposition comprises a polymeric layer having low permeability to air.18. The method of claim 15, wherein the air barrier composition includesa phase separated blend of elastomer and thermoplastic resin.